2-Alkynyladenosine derivatives, which have an alkynyl group at the 2-position of the adenosine base, have been accepted to be useful remedies for circulatory disorders such as hypertension (Japanese Patent No. 3053908). Also, the 2-alkynyladenosine derivatives have been known to exhibit an excellent effect of lowering ocular tension and to be a useful remedy for ophthalmological disorders, especially for glaucoma and ocular hypertension (WO00/12098).
However, the 2-alkynyladenosine derivatives, which have conventionally been reported to exhibit effect of lowering ocular tension, have the problem that they generally exhibit poor solubility in water. Poor solubility in water requires addition of a large amount of solubilizer when a liquid drug (e.g., an eye drop solution) is prepared, resulting in undesirable effects on stability and in terms of stimulation. In addition, interaction between the solubilizer and other additives may often occur, thereby raising limitations on preparation of drugs.
Accordingly, an object of the present invention is to provide an adenosine derivative which exhibits excellent pharmaceutical effects, such as effect of lowering ocular tension, and which have a high solubility in water, and drugs containing the derivative as an active ingredient.